U.S. patent application number 10/927306 was filed with the patent office on 2006-03-02 for work implement rotation control system and method.
This patent application is currently assigned to Caterpillar Inc.. Invention is credited to Patrick Michael Pecchio.
Application Number | 20060042804 10/927306 |
Document ID | / |
Family ID | 35745809 |
Filed Date | 2006-03-02 |
United States Patent
Application |
20060042804 |
Kind Code |
A1 |
Pecchio; Patrick Michael |
March 2, 2006 |
Work implement rotation control system and method
Abstract
A system for automatically moving a work implement of a work
machine includes a position monitoring system configured to track a
position of the work implement relative to a mapped landscape. A
controller is configured to change an angle of the work implement
relative to a direction of travel of the work machine in response
to information from the position monitoring system.
Inventors: |
Pecchio; Patrick Michael;
(Peorla, IL) |
Correspondence
Address: |
FINNEGAN, HENDERSON, FARABOW, GARRETT & DUNNER;LLP
901 NEW YORK AVENUE, NW
WASHINGTON
DC
20001-4413
US
|
Assignee: |
Caterpillar Inc.
|
Family ID: |
35745809 |
Appl. No.: |
10/927306 |
Filed: |
August 27, 2004 |
Current U.S.
Class: |
172/4.5 |
Current CPC
Class: |
E02F 3/842 20130101;
G05D 3/00 20130101 |
Class at
Publication: |
172/004.5 |
International
Class: |
E02F 3/76 20060101
E02F003/76 |
Claims
1. A system for automatically moving a work implement of a work
machine, comprising: a position monitoring system configured to
track a position of the work implement relative to a mapped
landscape; and a controller configured to change an angle of the
work implement relative to a direction of travel of the work
machine in response to information from the position monitoring
system.
2. The system of claim 1, wherein the controller is further
configured to adjust at least one of a slope of the work implement
and a height of the work implement in response to the information
from the position monitoring system.
3. The system of claim 1, the system further including a memory,
and wherein the controller is configured to initiate the change in
the angle of the work implement based on a location of at least one
predetermined area of the mapped landscape that is stored in the
memory and designated for an elevation change.
4. The system of claim 1, wherein the controller is further
configured to: determine a first difference between an actual
elevation and a desired elevation at a first location on the mapped
landscape; determine a second difference between an actual
elevation and a desired elevation at a second location on the
mapped landscape; and change the angle of the work implement
relative to the direction of travel based on a comparison of the
first difference and the second difference.
5. The system of claim 4, wherein at least one of the actual
elevation and the desired elevation at the first location is
pre-stored in a memory, and at least one of the actual elevation
and the desired elevation at the second location is pre-stored in
the memory.
6. The system of claim 4, wherein the controller is further
configured to rotate the work implement such that the work
implement deposits material at the first location if the first
difference is less than the second difference and at the second
location if the second difference is less than the first
difference.
7. The system of claim 1, wherein the controller is further
configured to: select a first predetermined location that is
designated for a decrease in elevation; select a second
predetermined location designated for an increase in elevation,
wherein the second location resides at a position forward of the
work machine; position the work implement to enable removal of
material from the first location; and automatically change the
angle of the work implement relative to the direction of travel to
deposit at least some of the material at the second location.
8. The system of claim 7, wherein the controller is further
configured to vary the rate at which the angle of the work
implement is changed based on the speed of the work machine in the
direction of travel and the distance to the locations of
predetermined cut and fill areas.
9. The system of claim 7, wherein the controller is further
configured to: maintain a longitudinal axis of the work implement
substantially orthogonal to the direction of travel after removing
the material from the first predetermined location to carry the
material over a distance prior to automatically changing the angle
of the work implement relative to the direction of travel.
10. The system of claim 1, wherein the work implement includes a
blade.
11. The system of claim 10, wherein the blade is attached to a
drawbar/moldboard/circle (DMC) assembly.
12. The system of claim 1, wherein the position monitoring system
is configured to track the position of the work implement in three
dimensions.
13. The system of claim 1, wherein the position monitoring system
is configured to generate a three dimensional map of the landscape
and store the map in a memory.
14. The system of claim 1, wherein the position monitoring system
is configured to make use of a global positioning system (GPS).
15. The system of claim 14, wherein the position monitoring system
includes a local positioning unit for supplementing the GPS.
16. A motor grader comprising: a cab: a traction system; a power
source; a work implement positionable at an angle relative to a
direction of travel of the motor grader; a position monitoring
system for tracking a position of the work implement relative to a
mapped landscape; and a controller configured to initiate movement
of the work implement, in response to information from the position
monitoring system, to change the angle of the work implement
relative to the direction of travel.
17. The motor grader of claim 16, wherein the work implement
includes a circle and the angle change is accomplished by rotation
of the circle.
18. The motor grader of claim 16, wherein the controller is further
configured to change the angle of the work implement relative to
the direction of travel based on a location of a predetermined area
of the landscape designated for an elevation change; wherein the
work implement includes a blade attached to a
drawbar/moldboard/circle (DMC) assembly; wherein the position
monitoring system is configured to track the position of the work
implement in three dimensions and is configured to generate a three
dimensional map of the landscape and store the map in a memory;
wherein the controller is further configured to vary a rate at
which the angle of the work implement is changed based on a speed
of the work machine in the direction of travel and a distance to
the location of the predetermined area; and wherein the position
monitoring system is configured to make use of a global positioning
system (GPS).
19. The motor grader of claim 16, wherein the controller is further
configured to: determine a first difference between an actual
elevation and a desired elevation at a first location; determine a
second difference between an actual elevation and a desired
elevation at a second location; and change the angle of the work
implement relative to the direction of travel based on a comparison
of the first difference and the second difference.
20. The motor grader of claim 16, wherein the controller is further
configured to: select a first predetermined location that is
designated for a decrease in elevation; select a second
predetermined location designated for an increase in elevation,
wherein the second location resides at a position forward of the
work machine; position the work implement to enable removal of
material from the first location; and automatically change the
angle of the work implement relative to the direction of travel to
deposit at least some of the material at the second location.
21. The motor grader of claim 20, wherein the controller is
configured to: maintain a longitudinal axis of the work implement
substantially orthogonal to the direction of travel after removing
the material from the first predetermined location to carry the
material over a distance prior to automatically changing the angle
of the work implement relative to the direction of travel.
22. A method of controlling a work implement for a work machine,
comprising: determining an actual position of a work implement
relative to a work site; locating, with respect to the actual
position, at least two predetermined areas designated for an
elevation change; and controlling an angle of the work implement
relative to a direction of travel of the work machine in response
to a relationship between the at least two predetermined areas
designated for an elevation change.
23. The method of claim 22, wherein one or more of the at least two
predetermined areas includes a fill area.
24. The method of claim 22, wherein one or more of the at least two
predetermined areas includes a cut area.
25. The method of claim 22, wherein the at least one predetermined
area designated for an elevation change is stored in a memory.
26. The method of claim 22, wherein controlling an angle of the
work implement includes: determining a first difference between an
actual elevation and a desired elevation at a first of the at least
two predetermined areas; determining a second difference between an
actual elevation and a desired elevation at a second of the at
least two predetermined areas; and changing the angle of the work
implement relative to the direction of travel based on a comparison
between the first difference and the second difference.
27. The method of claim 22, further including: selecting a first
predetermined location that is designated for a decrease in
elevation; selecting a second predetermined location designated for
an increase in elevation, wherein the second location resides at a
position forward of the work machine; removing material from the
first location; and automatically changing the angle of the work
implement relative to the direction of travel to deposit at least
some of the material at the second location.
28. The method of claim 27, further including: maintaining the
longitudinal axis of the work implement substantially orthogonal to
the direction of travel after removing the material and carrying
the material over a distance prior to automatically changing the
angle of the work implement relative to the direction of
travel.
29. The method of claim 22, further including: varying a rate at
which the angle of the work implement is changed based on at least
one of a speed of the work machine in the direction of travel and a
distance to one of the at least two predetermined areas designated
for an elevation change.
30. The method of claim 22, wherein the work implement includes a
blade.
31. The method of claim 30, wherein the blade is attached to a
drawbar/moldboard/circle (DMC) assembly.
32. The method of claim 22, further including: tracking the
position of the work implement in three dimensions with a position
monitoring system.
33. The method of claim 22, further including: generating a three
dimensional map of the work site; and storing the map in a
memory.
34. The method of claim 22, wherein the position monitoring system
is configured to make use of a global positioning system (GPS).
35. The method of claim 34, wherein the position monitoring system
includes a local positioning unit for supplementing the GPS.
Description
TECHNICAL FIELD
[0001] This disclosure is directed to a system and method for
controlling the movement of a work implement and, more
particularly, to a system and method for controlling the angle of a
work implement relative to a direction of travel of the work
machine.
BACKGROUND
[0002] Work machines such as motor graders, track-type tractors
(e.g. bulldozers), wheeled tractors, loaders, excavators, etc. can
perform many functions, which may require a control input device.
Controlling the many control input devices on a work machine may
require a highly skilled operator. Even with a skilled operator,
manual control of a work implement to accomplish many earth moving
tasks, particularly finish work such as finish grading, is not
always accurate and can require multiple trials to achieve a
desired result. Such duplication of work can be inefficient, time
consuming, and fatiguing to the operator.
[0003] Systems have been developed for automating certain functions
of a work machine in an attempt to improve efficiency and reduce
the skill level required to operate the machine. For example, U.S.
Pat. No. 5,375,663 ("the '663 patent") issued to Teach on Dec. 27,
1994, describes a system and method for automatic control of a
bulldozer blade based on mapped information correlated to a
worksite. The system of the '663 patent includes various laser
devices and sensors to track the height of the blade as the
bulldozer traverses the work site landscape. This system is
configured to automatically control the blade height based on the
location of the blade with respect to the worksite and the desired
elevation at that location.
[0004] Although the system of the '663 patent may improve grading
accuracy, and reduce the level of skill needed to operate the
machine, it does not make efficient use of each pass of the blade.
For example, while the system of the '663 patent includes automated
control of the amount of material cut from a particular location at
a worksite, the system does not include automated features for
efficient distribution of the material to other areas of the
worksite.
[0005] The disclosed control system is directed towards overcoming
one or more of the problems set forth above.
SUMMARY OF THE INVENTION
[0006] In one aspect, the present disclosure is directed to a
system for automatically moving a work implement of a work machine.
The system includes a position monitoring system configured to
track a position of the work implement relative to a mapped
landscape. The system may also include a controller, which may be
configured to initiate movement of the work implement in response
to information from the position monitoring system to change the
angle of the work implement relative to a direction of travel.
[0007] In another aspect, the present disclosure is directed to a
motor grader including a cab, a traction system, a power source,
and a work implement positionable at an angle relative to a
direction of travel of the motor grader. The position monitoring
system may track the position of the work implement. The motor
grader may also include a controller, which may be configured to
initiate movement of the work implement in response to information
from the position monitoring system to change the angle of the work
implement relative to the direction of travel.
[0008] In another aspect, the present disclosure is directed to a
method of controlling a work implement for a work machine. The
method includes determining an actual position of a work implement
relative to a work site. At least two predetermined areas
designated for an elevation change may be located with respect to
the actual position of the work implement. An angle of the work
implement relative to a direction of travel of the work machine may
be controlled in response to a relationship between the at least
two predetermined areas designated for an elevation change.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a diagrammatic illustration of a work machine
according to an exemplary disclosed embodiment;
[0010] FIG. 2 is a diagrammatic exploded view illustration of a
drawbar-circle-moldboard assembly according to an exemplary
disclosed embodiment;
[0011] FIG. 3a is a diagrammatic top view representation of a work
implement blade swivel motion according to an exemplary disclosed
embodiment;
[0012] FIG. 3b is a diagrammatic side view representation of a work
implement blade tilt motion according to an exemplary disclosed
embodiment;
[0013] FIG. 3c is a diagrammatic front view representation of a
work implement blade height adjustment according to an exemplary
disclosed embodiment;
[0014] FIG. 3d is a diagrammatic front view representation of a
work implement blade slope adjustment according to an exemplary
disclosed embodiment;
[0015] FIG. 3e is a diagrammatic front view representation of a
work implement blade side shift motion according to an exemplary
disclosed embodiment;
[0016] FIG. 4 is a block diagram representation of a work implement
control system according to an exemplary disclosed embodiment;
[0017] FIG. 5 is a diagrammatic top view representation of a motor
grader at a work site according to an exemplary disclosed
embodiment;
[0018] FIG. 6 is a flow chart of an exemplary process for
controlling work implement angle according to an exemplary
disclosed embodiment;
[0019] FIG. 7 is a flow chart of another process for controlling
work implement angle according to an exemplary disclosed
embodiment;
DETAILED DESCRIPTION
[0020] FIG. 1 illustrates an exemplary embodiment of a work machine
10, which includes a system for automatically moving a work
implement 12. Although-work machine 10 is shown as a motor grader,
work machine 10 may include other types of work machines such as,
for example, track-type tractors (e.g. bulldozers), wheeled
tractors, loaders, excavators, and any other type of work machine.
Work machine 10 may include work implement 12, a cab 14, a power
source 16, one or more traction devices 18, and position monitoring
system components 20, including a controller 22, one or more Global
Positioning System (GPS) receivers 24, a processor 26, and a
monitor display 28.
[0021] In an exemplary embodiment, work implement 12 may include a
blade 30. In the case of a motor grader, blade 30 may be attached
to a drawbar/moldboard/circle assembly (DMC) 32, as shown in FIG.
2. DMC 32 may include a drawbar 34, a moldboard 36, and a circle
38. Blade 30 may be attached to circle 38, which may be rotatably
attached to moldboard 36. Moldboard 36 may be attached to drawbar
34, which may be attached to a front portion 40 of work machine 10
with a pivoting joint 42. Circle 38 may swivel about an axis 44 in
a direction 46. Because circle 38 may be rotatably attached to
moldboard 36 and fixedly attached to blade 30, rotation of circle
38 may translate into swivel of blade 30.
[0022] Blade 30 may be adjusted in several degrees of freedom. FIG.
3a is a top view of blade 30 showing a swivel motion of blade 30. A
dashed element 48 represents blade 30 after it has been swiveled.
Swivel of blade 30 results in a change in an angle 50 of blade 30
relative to a direction of travel 52 of work machine 10.
[0023] In addition to swivel, blade 30 may also be tilted forward
and back. FIG. 3b is a side view of blade 30 showing a tilt motion
of blade 30. A dashed element 54 represents blade 30 after it has
been tilted. Tilt of blade 30 occurs when an upper edge 56 of blade
30 and/or a lower edge 58 of blade 30 are shifted forward and/or
rearward with respect to one another to change an angle 60 between
an axis 62 of blade 30 and direction of travel 52.
[0024] For purposes of this disclosure, the term "rotation" refers
to either or both of swivel and tilt of work implement 12, as
described above. For example, "rotation" of blade 30 may include
any motion resulting in a change in angle 50 and/or angle 60.
[0025] In addition to rotation, blade 30 may be raised and lowered
to adjust a height of blade 30. FIG. 3c illustrates a change in a
height 64 of blade 30 off a work surface 66 (e.g. the ground). A
dashed element 68 represents blade 30 after it has been raised.
[0026] FIG. 3d illustrates a change in the slope of blade 30. A
dashed element 70 represents blade 30 after a change in slope.
Slope is a function of a difference between a height 72 at a first
end 74 of blade 30 and a height 76 at a second end 78 of blade 30.
The slope may be determined by dividing the difference between
height 72 and height 76 by a length 80 of blade 30. Adjusting the
slope can change an angle 82 between a longitudinal axis 84 of
blade 30 and work surface 66.
[0027] FIG. 3e illustrates a side shift motion of blade 30 by a
distance 86. A dashed element 88 represents blade 30 after a side
shift.
[0028] Referring to FIG. 4, work machine 10 may include a position
monitoring system 90, which may be configured to track the position
of work implement 12 relative to a mapped landscape. Position
monitoring system 90 may include controller 22, GPS receivers 24,
processor 26, monitor display 28, a memory 92, an angle position
sensor 94, and a slope sensor 96.
[0029] Position monitoring system 90 may include memory 92 for
storing information. Memory 92 may be incorporated into a unit with
controller 22 or with processor 26 or in a single unit including
both controller 22 and processor 26. Memory 92 may store maps of a
work site. The maps may include elevation maps of the existing
landscape, as well as maps reflecting the desired contour of the
work site. The maps may also include differential maps illustrating
the differences in elevation between the existing landscape and the
desired contour of the work site.
[0030] The maps may be generated by position monitoring system 90.
The maps may be generated by driving around a worksite collecting
information along the way. By driving over the entire worksite,
position monitoring system 90 may record the actual elevation at
each area of the work site. Position monitoring system 90 may
generate a map of the worksite from this recorded elevation
data.
[0031] Also, processor 26 may be configured to superimpose or
compare elevation maps of the existing landscape at a worksite to
maps of the desired contour of the worksite. From the comparison,
processor 26 may generate maps indicating locations of
predetermined areas of the mapped landscape that are designated for
an elevation change. The designation of areas, at the work site,
for an elevation change may be established for the entire work site
prior to beginning operation of work machine 10 or may be
established as work machine 10 traverses the work site.
[0032] In addition, maps may be downloaded or programmed into
position monitoring system 90 from an outside source. For example,
when a machine is designated for use at a particular work site,
pre-established maps of that work site may be downloaded into
memory 92. Downloading or programming of information into memory 92
may be performed using external devices such as laptops, PDAs, etc.
Information transfer to memory 92 may also be performed wirelessly
with a network connection to laptops, PDAs, etc., or to a central
server at an offsite location.
[0033] Memory 92 may also store other information, such as, for
example, positional information about work machine 10, positional
information about work implement 12, and positional information
about obstacles at the work site. This information may also be
incorporated into one or more maps of the worksite.
[0034] Position monitoring system 90 may also include monitor
display 28 in cab 14 for displaying information to an operator.
Monitor display 28 may be any kind of display, including screen
displays, such as, for example, cathode ray tubes (CRTs), liquid
crystal displays (LCDs), plasma screens, and the like.
[0035] Monitor display 28 may display maps stored in memory 92 or
maps generated by position monitoring system 90. Monitor display 28
may also represent the past, present, and/or projected future
position and orientation of work machine 10 and work implement 12
in relation to the maps. For example, monitor display 28 may show a
trail indicating where work machine 10 has traveled within the work
site. Similarly, monitor display may show a projected route based
on the current heading of work machine 10, or a suggested route for
the operator to follow. Monitor display 28 may also display other
information unrelated to position monitoring system 90, such as,
for example, the amount of time the machine has been operating,
work machine systems information (e.g. oil pressure, hydraulic
fluid pressure, coolant temperature, etc.), and any other
information desired to be displayed to the operator.
[0036] Position monitoring system 90 may further include processor
26. Processor 26 may be located at any suitable location on work
machine 10. Processor 26 may be contained in its own housing or,
alternatively, may be housed with other components of work machine
10.
[0037] Processor 26 may receive information from any source from
which information is desired to be processed. In particular,
processor 26 may receive information about the position and
orientation of work implement 12 as well as the speed of work
machine 10. Processor 26 may receive this information from GPS
receivers 24, angle position sensor 94, slope sensor 96, and a work
machine speed sensor. Processor 26 may also receive information
from memory 92.
[0038] Processor 26 may be configured to determine which movements
of work implement 12 are desired and at what rate they should be
made, based on information it receives. Processor 26 may send
signals to controller 22 communicating these desired movements.
Processor 26 may also be configured to send signals to monitor
display 28 to display the information that processor 26 receives
and/or processes.
[0039] Controller 22 may also be located anywhere on board work
machine 10. Controller 22 may be contained in its own housing or,
alternatively, may be housed with other components of work machine
10, including for example, processor 26. Controller 22 and
processor 26 may be independent components if, for example,
position monitoring system 90 has been retrofitted to work machine
10, wherein work machine 10 was already equipped with controller
22. As a further alternative, one of controller 22 and processor 26
may be omitted and its functions performed by the other.
[0040] In any of the aforementioned arrangements, controller 22 may
be configured to receive information from processor 26 regarding
the desired movements of work implement 12. Controller 22 may also
be configured to initiate movements of work implement 12 in
response to information from processor 26. Controller 22 may be
configured to initiate swivel, tilt, height adjustment, slope
adjustment, side shift, and any other desired movements of work
implement 12. In addition, controller 22 may be configured to vary
the rate of rotation of work implement 12 as determined by
processor 26, based on the speed of work machine 10 and/or a
distance to a predetermined cut or fill area.
[0041] Position monitoring system 90 may be configured to track the
position of work implement 12 in three dimensions. By using this
tracking function, position monitoring system 90 may also update
the elevation maps of a work site as work implement 12 modifies the
contour of the landscape. In order to do this, the height and slope
of work implement 12 may be recorded as work implement 12 engages
the landscape at each location while work machine 10 traverses the
work site. This recorded information may be used to update a map of
actual elevation at the work site.
[0042] Position monitoring system 90 may also include one or more
GPS receivers 24 for receiving signals from one or more GPS
satellites 98. A local positioning unit 100 may be used to
supplement GPS receivers 24. Local positioning unit 100 may be a
reference station, at or near the work site, which enables GPS
receivers 24 to more accurately monitor the position of work
implement 12.
[0043] In operation, each of GPS receivers 24 may communicate with
one or more GPS satellites 98 to determine its position with
respect to a selected coordinate system. GPS receivers 24 may be
attached to one or more locations on work implement 12, preferably
at one or both ends.
[0044] A single GPS receiver 24 mounted on work implement 12 may
determine the position of work implement 12 relative to a mapped
landscape. With more than one GPS receiver 24, the orientation of
work implement 12 may also be determined. In an exemplary
embodiment, work implement 12 may have two GPS receivers 24 mounted
on it. The two GPS receivers 24 may be placed at or near the ends
of work implement 12, so as to determine the position of each of
ends. By knowing the position of each end of work implement 12,
processor 26 may determine the orientation of work implement 12.
For example, processor 26 may determine swivel angle by determining
the position of the two ends of work implement 12 relative to one
another. Similarly, processor 26 may determine the slope of work
implement 12 by comparing the height of one end of work implement
12 to the height at the other end.
[0045] While two GPS sensors 24 may be mounted on work implement
12, certain embodiments may include just one GPS sensor 24 mounted
on work implement 12. In an exemplary embodiment, work implement 12
may have a single GPS sensor 24 at one end for determining its
location at a work site. Angle position sensor 94 may be included
on work implement 12 for determining swivel angle. Work implement
12 may also include slope sensor 96 for detecting the slope of work
implement 12. The position and height at one end of work implement
12 may be determined by GPS receiver 24. The swivel angle of work
implement 12 may be determined by angle position sensor 94, rather
than by determining the position of both ends of work implement 12
with GPS receivers 24. Similarly, the slope of work implement 12
may be determined by slope sensor 96 rather than by comparing
heights measured by GPS receivers 24 at both ends of work implement
12.
[0046] Local positioning unit 100 may be any system for determining
the position of work implement 12 in a coordinate system. Local
positioning unit 100 may be placed at a surveyed location with a
known position. Local positioning unit 100 may be part of a
differential GPS, and may include a GPS receiver 102. GPS receiver
102 may be able to determine the position of local positioning unit
100. Position monitoring system 90 may compare the known (surveyed)
position of local positioning unit 100 with the position determined
by GPS receiver 102. Position monitoring system 90 may calculate a
correction factor for any error in the position determined by GPS
receiver 102. This correction factor may be used to correct errors
in the positions determined by GPS receivers 24 on work implement
12. Correction of these errors may enable a more accurate position
of GPS receivers 24 (and therefore work implement 12) to be
determined.
[0047] Alternatively, local positioning unit 100 may be a
laser-based system for determining the position of work implement
12 in the work site. Local positioning unit 100 may include a
transceiver for communicating with work machine 10. Such systems
may be used in a similar manner to a differential GPS as discussed
above to improve the accuracy of position monitoring system 90.
[0048] FIGS. 5-7, which are discussed in the following section,
illustrate the operation of a work machine utilizing embodiments of
the disclosed system.
INDUSTRIAL APPLICABILITY
[0049] The disclosed system may be applicable to a variety of work
machines, including motor graders, track-type tractors (e.g.
bulldozers), wheeled tractors, loaders, excavators, and any other
work machine that may include a work implement. The disclosed
system provides automation of work implement motion that can
increase efficiency and accuracy of work machine operations. For
example, the use of earth-moving work machines can involve the
movement of earth or other materials from one place to another. It
may be desirable to remove material from one location and deposit
the same type of material at a different location. The disclosed
control system can automatically move work implement 12 such that,
during any given pass of work implement 12, material removed from
one location may be automatically deposited at one or more desired
locations.
[0050] FIG. 5 depicts an exemplary work machine 10 within an
exemplary work site. Selection of a desired location to deposit
material may depend, at least in part, on its proximity to the
location from which the material was removed. For example,
processor 26 may analyze information about a work site within a
work zone 104, in proximity to work machine 10, to determine which
areas within work zone 104 are designated to have material removed
and which are designated to have material added.
[0051] A work zone may be of any size or shape. In an exemplary
embodiment shown in FIG. 5, work zone 104 may be an area around
work machine 10, within which work machine 10 could travel during a
predetermined period of time. For example, work zone 104 could
include all areas that work machine 10 could cover, at its current
speed, within the next few seconds or minutes.
[0052] Work zone 104 may include at least the area directly ahead
of work machine 10, and may be at least as wide as work implement
12. In addition, work zone 104 may also be expanded to include all
areas that the machine could cover if it were steered to one side
or the other. This expanded portion of work zone 104 may be
generally the shape of a baseball diamond, as shown in FIG. 5.
Also, because work machine 10 may deposit material to the side of
the machine (by swiveling work implement 12 to one side), work zone
104 may be wider than work implement 12.
[0053] The size and shape of work zone 104, as well as the
predetermined period of time, may be fixed at universally effective
values for all operating conditions of work machine 10. As an
alternative, these values may be automatically adjusted to suit the
current operating conditions of work machine 10. As a further
alternative, these values may be chosen by an operator to suit the
current task. Further still, modes may be selected between these
alternatives to allow an operator to choose between fixed values,
automatic adjustment, manual settings, and combinations
thereof.
[0054] As work machine 10 traverses the work site, processor 26 may
analyze the landscape in work zone 104 and determine which areas
require elevation changes. Processor 26 may select, from these
areas, those that will be involved in the next one or more
movements of work implement 12.
[0055] Although the located areas may be selected from a collection
of predetermined areas within work zone 104, they may,
alternatively, be selected in any suitable manner from amongst all
areas at the work site that have been designated for an elevation
change. In such a case, processor 26 may determine an intended
route, covering the entirety of the work site and select
predetermined areas designated for an elevation change along the
entire route. As yet another alternative, processor 26 may analyze
the areas designated for an elevation change for the whole work
site and determine an intended route based on the location of those
areas.
[0056] One method of operation may include determining differences
between the actual and desired elevations for at least a first area
106 and a second area 108 designated for an elevation change, as
shown in FIG. 5. Swivel of work implement 12 may be controlled to
deposit material in the area where the difference is determined to
be greatest. In other words, work machine 10 determines which of
areas 106 and 108, is furthest below or least above the desired
elevation and deposits the material there.
[0057] Another method of operation may include selecting a location
designated for a decrease in elevation, such as a cut area 110, and
a location designated for an increase in elevation, such as area
108, which may be a fill area. Material may be removed ("cut") from
cut area 110 and automatically deposited at area 108 by swiveling
work implement 12.
[0058] In situations where a selected cut area 110 and fill area,
such as area 108, are not directly adjacent one another, it may be
desirable to carry material removed from cut area 110 over a
distance 112 prior to depositing it at a fill area, such as area
108. In these situations, controller 22 may maintain longitudinal
axis 84 of work implement 12 substantially orthogonal to direction
of travel 52 after removing the material. Doing so may enable work
implement 12 to carry the material over distance 112 prior to
automatically swiveling to deposit the material at area 108.
[0059] The rate of swivel of work implement 12 may be linked to the
speed of work machine 10. For example, the rate of swivel may
increase with the speed of work machine 10. Conversely, the rate of
swivel may also be decreased as the speed of work machine 10
increases. The relationship may or may not be linear and may be
described with many different functions, including, but not limited
to, non-linear functions, step functions, and exponential
functions. The relationship between rate of swivel and the speed of
work machine 10 may be varied during operation of work implement
12. For example, rate of swivel may decrease linearly as the speed
of work machine 10 decreases, but, as the speed of work machine 10
approaches zero, the rate of swivel may decrease less rapidly, so
as to avoid reducing the rate of swivel too much. Similarly, as the
speed of work machine 10 approaches its maximum, the speed of
swivel may increase less rapidly, so as to avoid swiveling too
fast, or too much.
[0060] The rate of swivel may also depend on the distance between
work machine 10 and predetermined cut and fill areas. This
relationship may vary as greatly as the relationship between rate
of swivel and the speed of work machine 10 discussed above. Also,
the relationship may be varied during operation of work implement
12. For example, when a cut area, such as cut area 110, as shown in
FIG. 5, is relatively close to a fill area, such as area 108, work
implement 12 may be required to swivel significantly over a short
distance 112 of machine travel. Therefore, initially, the short
distance 112 to area 108 would require a relatively fast swivel of
work implement 12. However, as work machine 10 approaches area 108
(i.e. as a distance 114 from work machine 10 to area 108 approaches
zero) and angle 50 of work implement 12 approaches the desired
angle, the rate of swivel would slow down.
[0061] The desired change in elevation at any given location may be
great enough that the entire change may not be possible to achieve
with a single pass of work implement 12. Controller 22 and position
monitoring system 90 may be configured to take this into account
and limit the amount of material that work implement 12 may remove
in a single pass. This may be accomplished by limiting the depth
below the actual elevation at which work implement 12 may be set
and/or by monitoring the actual load on work implement 12.
[0062] The load on work implement 12 during operation may also
affect swivel of work implement 12. For example, while material is
being carried from one location to another, work implement 12 must
remain in contact with the ground. As a result, additional material
may be loaded onto work implement 12 during this process. Because
of this, it may not be practical to maintain work implement 12
substantially orthogonal to direction of travel 52, if doing so
would cause an amount of material to load on work implement 12 that
exceeds its load limit. Accordingly, while carrying material, work
implement 12 may be automatically swiveled based on the monitored
load, in order to deposit some material along the way, so as to
maintain an acceptable load on work implement 12.
[0063] FIG. 6 illustrates one possible method of depositing
material. At step 116, position monitoring system 90 may determine
an actual position of work implement 12 relative to a work site.
This position may be determined by processor 26, using information
from one or more GPS receivers, as discussed above.
[0064] At 118, processor 26 may update the actual elevation in one
or more maps stored in memory 92. As discussed above, this update
may be conducted by recording the height and slope of work
implement 12 as work machine 10 traverses the work site.
[0065] At 120, position monitoring system 90 may locate, with
respect to the actual position of work implement 12, at least two
predetermined areas designated for an elevation change. These
predetermined areas may be selected from an analysis of the entire
work site or a smaller subset thereof.
[0066] At 122, processor 26 may determine a first difference
between an actual elevation and a desired elevation at a first
predetermined area and a second difference between an actual
elevation and a desired elevation at a second predetermined area.
These differences may be determined by comparing an elevation map
of the existing landscape at the work site with an elevation map of
the desired contour of the landscape. At 124, a comparison may be
made between the first difference and the second difference.
Comparing these differences determines which of these two areas is
most appropriate for depositing additional material.
[0067] At 126, controller 22 may control swivel of work implement
12 based on the comparison between the two differences.
Specifically, controller 22 may swivel work implement 12 to deposit
material at the predetermined area that is furthest below the
desired elevation or least above the desired elevation, in
comparison to the other located area or areas. For example, work
machine 10 may remove material from a cut area and processor 26 may
determine where to deposit the material by determining which of a
plurality of fill areas is furthest below the desired elevation at
its respective location. The process may repeat, continuously
analyzing the landscape and controlling work implement 12 based on
that analysis.
[0068] FIG. 7 illustrates one possible method of moving material
from one location to another. In this method, processor 26 may also
follow steps 116-120 described in connection with FIG. 6. In
addition, at 128, processor 26 may select a first predetermined
location that is designated for a decrease in elevation, and at
130, may select a second predetermined location, forward of work
machine 10 that is designated for an increase in elevation. These
locations may be selected in a number of ways, as discussed above,
from maps of the work site stored in memory 92.
[0069] At 132, work implement 12 may be used to remove material
from the location designated for a decrease in elevation. As work
machine 10 passes over the location designated for a decrease in
elevation, the height and slope of work implement 12 may be
automatically controlled to remove a desired amount of
material.
[0070] At 134, controller 22 may maintain longitudinal axis 84 of
work implement 12 substantially orthogonal to direction of travel
52 of work machine 10. Work implement 12 can be maintained in this
orientation while work machine 10 is proceeding from the first
location to the second location to carry the material to the second
location as needed.
[0071] At 136, with work implement 12 loaded with material,
controller 22 may automatically swivel work implement 12 to deposit
at least some of the material at the second location to thereby
increase the elevation at the second location. This process may
repeat continuously as well.
[0072] It will be apparent to those skilled in the art that various
modifications and variations can be made to the disclosed work
implement control system without departing from the scope of the
invention. Other embodiments of the invention will be apparent to
those skilled in the art from consideration of the specification
and practice of the invention disclosed herein. It is intended that
the specification and examples be considered as exemplary only,
with a true scope of the invention being indicated by the following
claims and their equivalents.
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